Consider the pushdown automation (PDA) P below, which runs on the input alphabet {a, b}, has stack alphabet {$$\bot$$, A}, and has three states {s, p, q}, with s being the start state. A transition from state u to state v, labelled c/X/$$\gamma$$, where c is an input symbol or $$\in $$, X is a stack symbol, and $$\gamma$$ is a string of stack symbols, represents the fact that in state u, the PDA can read c from the input, with X on the top of its stack, pop X from the stack, push in the string $$\gamma$$ on the stack, and go to state v. In the initial configuration, the stack has only the symbol $$\bot$$ in it. The PDA accepts by empty stack.

Which one of the following options correctly describes the language accepted by P?

Consider the following languages:

$$\eqalign{ & {L_1} = \{ ww|w \in \{ a,b\} *\} \cr & {L_2} = \{ {a^n}{b^n}{c^m}|m,\,n \ge 0\} \cr & {L_3} = \{ {a^m}{b^n}{c^n}|m,\,n \ge 0\} \cr} $$

Which of the following statements is/are FALSE?

Suppose that L₁ is a regular and L₂ is a context-free language, Which one of the following languages is NOT necessarily context-free?

Consider the following context-free grammar where the set of terminals is {a, b, c, d, f}.

S → d a T | R f

T → a S | b a T | ϵ

R → c a T R | ϵ

The following is a partially-filled LL(1) parsing table.

Which one of the following choices represents the correct combination for the numbered cells in the parsing table ("blank" denotes that the corresponding cell is empty)?